1. Field of the Invention
The present invention generally relates to temperature sensing probes. More particularly, the present invention relates to a temperature gradient sensing probe for monitoring hyperthermic medical treatment of tissue.
2. Description of the Prior Art
According to U.S. Pat. No. 4,397,314, hyperthermia is defined as the heating of living tissue for therapeutic purposes. The high heat contributes to the natural regression or remission of tumors. Generally, in hyperthermic medical treatments, a controllable temperature level elevation at preselected locations and volumes of tissue is utilized to treat patients with cancer or other diseases.
According to U.S. Pat. No. 4,960,109, satisfactory hyperthermic treatment requires the ability to produce specific, well-characterized temperature elevations in precisely selected volumes of tissue that comprise the malignancy. This, in turn, requires the capability of measuring and controlling the temporal and spatial characteristics of an absorbed thermal dose so as to produce the desired temperature distribution for the specific malignancy being treated.
In U.S. Pat. No. 4,397,314, a linear array temperature probe is disclosed. The disclosed probe is comprised of a number of sensors which are ensheathed in a protective plastic catheter. The sensors are connected to a circuit via pairs of optic fiber cables. One of the fiber optic cables transmits monochromatic radiant energy to a gallium arsenide temperature sensor. Another fiber optic cable transmits a reflected ray, the intensity of which is a function of the temperature of the semiconductor sensor.
Due to the delicate nature of optical fibers, the described temperature probe is believed to be relatively expensive to manufacture because very careful handling is required. Because such probes are believed to be expensive as a result of the delicate nature of the optical fiber, it is likely that such probe will not be discarded after use, but instead, carefully handled and placed in an autoclave to be sterilized. Such additional after treatment handling further adds to the cost of using such probes. Thus, the costs of manufacturing and use of the described probe are believed to be relatively high, and potentially prohibitive.
In U.S. Pat. No. 4,960,109, a multi-function probe or needle for use in hyperthermia therapy is disclosed. The probe employs at least one pair of temperature sensors which may be thermocouples or thermistors. These sensors are connected to a measuring circuit via small conductive leads. The handling, strain relief, termination of small wires is difficult, expensive and not very reliable. Thus, because such probes tend to be very small so as to be minimally invasive when inserted into a patient, the manufacturing costs of affixing the sensors to the probe and the threading of leads in the probe are likely to be very high, making such probes expensive to purchase. As discussed above, these probes are also not likely to be discarded, but reused after sterilization procedures are performed, further adding to the cost of using such probes.
It is desirable to provide a hyperthermic temperature gradient sensing probe which is relatively inexpensive to manufacture. It is also desirable to provide a probe that is inexpensive to use, accurate and that may be discarded after use to reduce the cost of after treatment handling.